Carburetor



Jul 14, 1931.

E. F. GEIGER CARBURETOR Filed June 25, 1928 ilmoev to'c Patented July it rest stares torture pnwann r. omens, or mussels/iron, new roan CARB'URETOR Application filed June 25,

This invention relates to improvements in carburetors and has for its object the provision of improved means for controlling the quality of the fuel mixture,

Provision is made for controlling the fuel quality through the commonly used operating range primarily by the speed of the engine and secondarily by the degree of throttle opening so that at low engine speeds at any throttle opening the fuel mixture will be relatively rich and at high engine speeds with partially closed throttle conditions the mixture will be relatively lean and with widely open throttle conditions at high engine speeds the mixture will be of medium rich quality,

The present invention has for its object the provision of novel means for securing the aforesaid fuel mixture quality,

A. further object of the present invention resides in the provision of a novel means for exerting a. variable resistance to the action a controlling valve in accordance with the operating conditions of the engine,

the drawing:

The figure 1 shows substantially central vertical sectional view of my improved car= huretoro more detail the carburetor comprises the usual well known parts such as a riianifold connection or outlet conduit 1 having associated therewith a mixture conduit 2 provided with a throttle valve 3 operated in the usual manner. There is also a Venturi section 4: disposed at the entrance of the mixture conduit 2; an air inlet 5 provided with a conventional choke valve 6 operated in the usual manner and a constant level float chamber 7 which is supplied with fuel through pipe 8. A fuel nozzle 9 extends into the constricted portion of venturi l and is supplied with fuel from the constant level reservoir 7 by means of passages l0, l1, l2 and 13, To control the flow of fuel to the nozzle 9 a needle valve ll is provided. A tube open to the atmosphere at its lower end extends into fuel nozzle and serves to conduct air to the upper end of the latter which air assists in atomizing the fuel when the carburetor is in operation, Disposed at an intermediate point 1928. Serial No. 287,908.

between the Venturi section f and the air inlet conduct 5 is an air valve 16 yieldingly moved towards its closed position by a spring 17 and having a stem or guide member 18 which extends up and slidably fits in a cylindrical bore 19 of the carburetor body. This cylindrical bore 19 is connected at its upper end with the mixture conduit 2 by means of a passage 20 which extends into the mixture conduit at a point adjacent the throttle valve 3 and at a point on the Venturi side thereof when the said throttle valve is in nearly closed position. A needle valve 204; is provided to limit the effective opening of passage 20. An auxiliary duct 21 is also provided between the upper end of the cylindrical bore 19 and the mixture conduit Such auxiliary passage or duct enters the mixture conduit at a point somewhat nearer the venturi than the point of entrance of passage 20 In order to prevent the air valve 16 from entirely'closing adjustable stop member 22- is provided. In the operation of the carburetor, the

pumping action of the associated engine produces a depression of pressure in mixture conduit 2 which causes the airto flow through air inlet 5 past valve 16 and through the venturi a. This depression of pressure also causes fuel to flow from the float chamber past the needle valve 14, through passages l2, l1 and 10 and out of nozzle 9 into the venturi a where it becomes commingled with the air flowing therethrough to thereby formthe fuel mire tpre required to operate the engine.

The quality of the fuel mixtures is modified to meet the requirements of the engine at various speeds and power outputs by means of the air valve 16, which by oifering resistance to the flow of air from the air inlet 5 to the venturi 4 produces a greater depression of pressure in the venturi than would otherwise normally maintain there for any given air speed; pressure in the venturi produces a corresponding increase in the flow of fuel from the nozzle 9 with a consequent enrichment of the fuel mixture. The disposition of passage 20 with respect to the throttle valve 3 is such that when the latter is opened somewhat,v for eX ample to the position marked the depres- Eli till

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uch increase of depression of sion in pressure existing in the mixture conduit 2 upon the engine side of the throttle is efiective to reduce the pressure in chamber or bore 19. In such bore the upper part of 18 acts as a piston or plunger and is drawn upwardly by the depression of pressure in 19 so that this action tends to and pulls up valve 16 against the action of the spring 17 and thus tends to reduce air valve 16 to the flow of air to the venturi. The ultimate action is that the depression of pressure in the venturi is proportionately reduced whereby the amount of fuel entering the air stream is proportionately reduced. It may be also stated that the depression of pressure above the throttle 3 is greater than that below it. Accordingly, this pressure difference is available to bring about action of the piston 18. 20

As the engine speed increases the depression of pressure upon the engine side of the throttle valve 3 increases, thereby increasing the depression of pressure in bore 19 and further lessening the efiect of valve 16 to produce an enrichment of the fuel mixture. At high engine speeds, the depression of pressure on the engine side of throttle valve 3 may become great enough to pull the valve 16 entirely up. Under suc conditions the valve 16 will offer no resistance to the flow of air to the venturi and the amount of fuel fed into the air stream will depend entirely upon the normal depression of pressure caused by the action of the venturi and by the setting of the fuel needle valve 14. This needle valve may be set to furnish a very lean mixture if 7 desired under the last mentioned operating conditions. a x

The object of the auxiliary passage 21 is to somewhat modify and lessen the effect of passage 20 upon the piston-like stem of valve 16 so'that the latter functions more in accordance with the speed of the engine than would be the case i passage 20alone were provided. The depression in pressure on the engine side of the throttle valve 3 reaches its greater value under nearly closed throttle conditions and even at slow engine speeds under these conditions this depression of pressure may be greater than that whibh maintains at high engine s eeds under intermediate open thrdttle con itions. The aux-v iliary passage 21 tends to compensate for the above noted variation in pressures by allowmg air to flow into bore 19 through the passage 21 when the throttle valve is in a. nearly closed position such as 3a, therebylessening the effect of passage 20 under this condition. WVhen the throttle valve 3' is in a nearly closed position such as 3a, air will flow from the fuel mixture conduit 2 on the Venturi side of the throttlethrough auxiliary passage 21 into bore. 19 and out of the latter through passage conduit 2 on the engine side of the throttle 'out of the resistance oliered by the emme valve. The needle valve 20a may be adcomparatively less even at high engine speeds I than obtains under nearly closed throttle conditions. However, at such intermediate open throttle positions both passage 20 and auxiliary passage 21 are subject to the depression -of pressure upon the engine side of the throttle and such depression of pressure is communicated unrelieved to bore 19.

From the foregoing it will be understood that the throttle in accordance with its relative position with respect to 20 and 21 will modify the ultimate suction which is available to act upon 18. Higher suction effects are cut down when the throttle is in nearly closed positions and in relatively wider 0 en positions the full suction eflects are availa le without diminution.

18 which is in the form of a be provided with slight clearto allow some air to flow along The part plunger may ance if desired it into bore19 and in this way the action may be additionally varied. Various amounts of clearance may be provided 'asdesired.

It will be understood that at slow enginespeeds under medium open and open throttle conditions the suction conditions are such that there is comparatively littledepre ssion of pressure in bore 19 and accordingly unios der these conditions there is a relatively small supplementary pull upon the stem 18 so that the valve 16 acts in normal manner to enrich the mixture. 9 v

In accordance with the present-invention the means for varying the action of the air means takes into account the pressure conditions adj acent the throttle 3 and it is in accordance with these conditions that the action of enriching air valve is modified.

,VVhat I claimis: 1. A carburetor with a throttle, a venturi,

.an air resisting valve disposed in the intake 20 into the fuel mixture shutoil by the throttle when the latter moves to closed position.

-valve 16 is one which is disposedbetween the outlet conduit and the valve 16 itself. This nerenaa 2. A carburetor having a throttle, a venturi and an air valve disposed in the inlet to the venturi and having yielding means to resist opening movement thereof, in combination with a plunger connected to said valve, and ducts extending to a point adjacent the throt tle to exert suction effects upon the said plunger to thereby modify the action of the air valve in accordance with the pressure conditions adjacent the throttle, said means being shut ofl' by the throttle when the latter moves to closed position.

3. A carburetor having a controlling air valve with yielding means to resist opening movement thereof which air valve varies the degree of enrichment of the fuel mixture, an outlet conduit provided with a throttle, a venturi the aforesaid'controlling air valve being disposed in the air inlet to the venturi, means for supplying fuel to the venturi, and means intermediate the outlet conduit and said air valve for utilizing the suction efiects in the conduit adjacent the edge of the throttle for modifying the action of the mixture enriching air valve.

4. The invention set forth in claim 3 in which the means intermediate the outlet conduit and air valve comprises a plurality of ducts which variably cooperate with the throttle to modify the available suction effects in the conduit which are employed for controlling and modifying the action of the air valve.

5. A carburetor with an outlet conduit, a throttle valve, a venturi, an air controlling valve for modifying the richness of fuel mixture by controlling the intake to the venturi, resilient means for controlling the aforesaid valve, means for supplying fuel to the venturi, a chamber connected to the outlet conduit by passages which extend adjacent to the edge of the throttle in said conduit, both of said passages being disposed upon the venturi side of the throttle when the latter is'in closed position'and means in said chamber operatively connected to the air valve for modifying its action in accordance with pressure variations in said chamber.

6. In a carburetor having a venturi, means for supplying fuel thereto, an outlet conduit therefrom, a throttle valve therein, and an air flow resisting valve in the inlet to the venturi for varying the degree of enrichment of the fuel mixture, and means including a passage to the outlet conduit and brought into operation under the control of the suction conditions which exist above the throttle at high engine speeds for changing the resistance of said air valve whereby enrichment of the fuel mixture under these conditions is prevented said passage being shut off by said throttle when the latter is in closed position.

7 A carburetor having a venturi, a mixture outlet therefrom, an air valve in the inlet to the venturi, means comprising movsignature.

EDWARD F. GEIGER. 

